Caption: Pen and ink perspective drawing on paper by Leonardo from 1487 of a cannon foundry. It depicts the inside of a factory for casting cannons from bronze and the process of installing of a heavy cannon barrel on its wheeled gun carriage by a large number of labourers. The barrel is being hoisted entirely manually by means of block and tackle on a crane and levers. It also shows bronze barrels awaiting assembly and the necessary ancillary equipment.